A. Field of the Invention
This invention relates to the inhibition of the secretion of stomach acid in vertebrate animals and more particularly relates to inhibiting or slowing secretion of stomach acid by treating the animal, including human beings, with a chemical compound.
B. History of the Prior Art
The secretion of excess stomach acid has been associated with peptic ulcers, i.e., an ulcer occurring in the lower end of the esophagus, in the stomach, or in the duodenum. Furthermore, excess stomach acid has also been associated with heartburn and other stomach pains.
There have, therefore, been historic attempts to relieve excess stomach acid. Until recently, the effects of excess acid were relieved, with some success, through neutralization, diet and behavioral or emotional modification. The most common method for relieving excess stomach excess was by neutralization. Well known stomach acid neutralizers are, for example, sodium bicarbonate, magnesium hydroxide, calcium carbonate, aluminum hydroxide, aluminum phosphate, magnesium trisilicate, tribasic calcium phosphate, sodium carboxymethylcellulose, dihyroxyaluminum acetate, aluminum carbonate, and calcium tartrate. Certain polyamine methylene resins have also been tried.
Until recently, attempts were also made to inhibit the flow of gastric acid. Compounds which had been tried for this purpose were atropine sulfate and other atropine derivatives. These compounds were not uniformly effective and, in addition, created serious side effects including inhibition of the parasympathetic nervous system, dryness of the mouth, blurring of vision, heart palpitations and toxic psychosis.
Numerous other compounds for inhibiting acid secretion were tried but until recently, none of the compounds excelled in the combination of lowering the output of acid while at the same time, resulting in minimal side effects.
Recently, a compound has been introduced which has been found to be superior in reducing the flow of stomach acid. This compound, commonly known as cimetidine, has the imperical formula C.sub.10 H.sub.16 N.sub.6 S and has Chemical Abstracts Registration No. 51481-61-9. The compound has some structural similarity to histamine since similar to histamine, it has a heterocyclic imidazole ring. It is believed that the compound functions by entering the blood stream and interferes with histamine receptor sites on the nutrient side of the stomach wall (the side opposite the food containing or lumen side of the stomach wall). It is believed that cimetidine is effective in stopping the secretion of stomach acid by blocking the histamine sites since histamine is believed to be responsible for initiating the flow of stomach acid.
Unfortunately, while being effective in stopping acid flow, cimetidine has been found to have some undesirable characteristics. In particular, use of the cimetidine drug has been found to sometimes impair kidney function and cause mental confusion. There is also some evidence that after use of the drug is discontinued, acid rebound (secretion of acid at a higher than normal rate) can occur. There is furthermore some evidence that cimetidine can inhibit sperm production in adult males using the compound.